Field of Invention
The present disclosure generally relates to a method and device for tracking the reflected or transmitted spectral response of a perturbation sensor and more particularly to a method and device for tracking the spectral response of a perturbation sensor in an overlap condition.
Description of Related Art
Fiber Bragg grating sensors offer broad improvements to current systems for monitoring temperature and stress. For example, the oil and gas industry often requires the monitoring of the downhole environment of drilling sites. While the oil and gas industry often employs distributed temperature sensors and distributed acoustic sensors to measure temperature and stress, these sensors have undesirable long integration times (e.g., greater than five minutes). Fiber Bragg grating sensors, by contrast, are only limited to the time it takes signals to reflect from the sensors and return to the transceiver system, which is less than 10 microseconds per kilometer. Furthermore, fiber Bragg grating sensors offer the advantage of a much higher signal-to-noise ratio over other known solutions.
However, as temperature, strain, vibration, pressure, and acoustic signals vary around a fiber Bragg grating sensor, the reflected signal will vary in at least wavelength and magnitude. As shown in FIG. 1, subjected to enough temperature or stress, the wavelength of a reflected signal may vary to the point where it is overlapping the reflected signal of a separate fiber Bragg grating sensor. This overlap condition may introduce ambiguity into the measurement of the spectral response of a plurality of fiber Bragg grating sensors. More specifically, this may limit the number of sensors per fiber because the sensors need to be spaced such that the signal from one sensor will not overlap another. This ambiguity and resulting required spacing may limit the spatial resolution and the effectiveness of the fiber Bragg grating sensors.
Accordingly, there is a need in the art for a method and/or device that will accurately track the signals of a perturbation sensor in an overlap condition to reduce or eliminate ambiguity.